Almost 80% of Britons believe the £9 billion spent on the Olympic Games was value for money, according to a new poll that shows a lasting nostalgia for the nation's achievements.

A Guardian/ICM poll showed that 78% of voters believed the Olympics "did a valuable job in cheering up a country in hard times", as compared with just 20% who look back on them as "a costly and dangerous distraction".

The vote of confidence is even stronger than opinion taken at the Games' height.

In an online survey taken immediately after so-called Super Saturday - on which Mo Farah, Jessica Ennis and Greg Rutherford all took track and field gold for Team GB - 55% agreed and 35% disagreed with the same proposition.

Pollsters, who interviewed 1,002 adults, said the Paralympics may have helped to cement this majority. A crushing margin in favour of London 2012 was found in every social class and also in every region. Some had feared that the Games would be heavily concentrated in the capital and its hinterland, but in fact 79% support in the south was closely matched by 80%, 74% and 77% respectively in the Midlands, the north and in Wales.

Only the Scots were less enthusiastic, and even among them the overall 69%-31% balance was in favour of the Games.

The Olympics occupied little more than a fortnight during a year which also saw volatile weather, the Diamond Jubilee and the first double-dip recession since the 1970s. Asked to consider all of these things together, and reflect on 2012 as a whole, 49% of respondents said the year made Britain a better place to live - against 41% who said the opposite, suggesting a positive public take on the Olympics is colouring wider perceptions of the year.

The overall verdict ought to surprise voters themselves, who in last year's Guardian Christmas poll told ICM by a 60%-30% margin that they expected Britain would become a more miserable place in 2012. But if the Olympics bequeathed a feelgood legacy, it is not one politicians are cashing in on.

Pollsters said the Conservative party remains eight points behind Labour for the third month in a row. Compared with last month, all the main parties stand still, with Labour on 40%, the Tories on 32% and the Liberal Democrats on 13%.

Asked to award political leaders a school mark for their work in the last year Prime Minister David Cameron and opposition leader Ed Miliband both got a C-. The one figure to do much better was the Queen, who was top of the class with a solid B+.